1. Field of the Invention
The present invention relates to a collision avoidance system of a vehicle, and more particularly to a collision avoidance system of a vehicle that is capable of distinguishing the type of objects around a vehicle and the position and velocity of the objects relative to the vehicle.
2. Description of the Prior Art
There is a continuing increase in the density of vehicles on the road and a simultaneous emphasis on improving the safety of highway and ordinary roadway vehicles operation by preventing vehicles from colliding with stationary and moving objects. One means for accomplishing this is to detect or monitor the relative speed, the direction of travel, and the distance between vehicles sharing the roadway, and to use such information to provide direct indications to the vehicle's driver of potential danger.
For example, U.S. Pat. No. 6,037,860 issued Mar. 14, 2000 to Zander et al. and assigned to Volkswagen AG, teaches using a seat occupancy sensor to evaluate various collision strategies as an indicating function of possible severity of damage or injury. For this purpose, a collision strategy in which there are no injuries to persons is preferably selected, i.e. a collision with an inanimate object is carried out if this does not involve the driver and further vehicle occupants being subjected to excessive danger. For this purpose, the motor vehicle is actuated in such a way that most of the unoccupied areas of the vehicle absorb the impact energy, i.e. the vehicle is turned with the unoccupied areas towards the object with which it is colliding.
The Zander et al. system provides for a representation of the vehicle surroundings as determined by a number of laser sensors, radar sensors and thermal imaging and other cameras or a combination thereof. Thus, the Zander et al. system detects moving objects in the environment and internal vehicle conditions, in order to generate vehicle controls to avoid or minimize vehicle collisions. Sensor information is processed in an evaluation unit to determine a course of action and vehicle actuators implement the selected course of action. It would be desirable to have a more complete list of information regarding type of objects, distance from the host (including radial and angular information), and relative velocity. In particular, it would be desirable to have object-tracking data for visual awareness purposes, threat analysis, and possible subsequent vehicle actions. These are some of the problems the present invention overcomes.
Further, the Zander et al. patent generally alludes to combining of various sensor technologies to form a picture of the targets surrounding the vehicle. However, for any particular target at any particular time, there is no teaching of using more than one sensor to obtain target-tracking information. It would be desirable to teach combining sensor information in an explicit way such that each field around the host car is covered in duplicate by radar and a camera. Using a fusion combination, in accordance with an embodiment of this invention, the best and most useful data from the radar is combined with the best and most useful data from the camera.
U.S. Pat. No. 5,479,173 issued Dec. 26, 1995 to Yoshioka et al. and assigned to Mazda Motor Corporation teaches combining radar and camera data to determine a danger level of an object in the predicted path of the host car. It would still be desirable to build a complete picture of objects around the host car.
U.S. Pat. No. 5,475,494 issued Dec. 12, 1995 to Nishida et al. and assigned to Mitsubishi Denki Kabushiki Kaisha teaches gauging size and distance of objects based on a calculated two-dimensional image. The system looks forward only and does not use true radar sensing. Data from a single forward looking camera are combined with data from a set of laser radar sensors.